21/2+9/16* 1 5/27-3 3/7:27/28​

-7/18
1)9/16*32/27= 9*32/16*27=288/432= 2/3
2) 24/7:27/28= 24*28/7*27= 672/189= 224/63=32/9
3) 5/2+2/3 = 15/6+4/6=19/6
19/6-32/9= 57/18-64/18= -7/18